The number of homes sold jumped 17.7 percent to 865 from 735 in July 2011, while the median price rose a slight 0.3 percent over the year to $361,250.

That double-digit increase in activity was the second highest out of the six counties of Los Angeles, Riverside, San Diego, Ventura, San Bernardino and Orange that DataQuick covered in the report. Sales activity in Orange County experienced the greatest boost of 25.7 percent compared to a year ago.

Across the six counties, home sales rose 13.8 percent, and showed an increase for the seventh consecutive month. Median home prices rose to $306,000 last month, an 8.1 percent increase from a year ago and the highest median price since September 2008.

"There's certainly an increase in activity and sales are increasing compared to last year," said Realtor Shirley Acosta, With Re/Max Gold Coast in Camarillo. "There are lots of multiple offers out there. It's like a bidding war again."

She said inventory is "really low" at only two months, and that combined with historically low mortgage rates are fueling demand.

That low inventory also is boosting short sale activity, Acosta said, as people are willing to wait for bank approval. Another factor in the market is investors who are buying and then renting homes for the growing rental market, Acosta said.

Acosta said the county's median price range is closer to $400,000.

For the larger area, DataQuick attributes the boost in sales activity to increased demand from the "move-up and high-end submarkets."

DataQuick defines the move-up category as homes priced $300,000 to $800,000. Volume has surged 22 percent from a year ago.

Sales of homes priced more than $800,000 rose 7.2 percent from a year ago.

The real estate business attributed those increases to low mortgage rates, declining inventory and the "sharp drop" in low-end distressed homes sales, such as foreclosures and short sales.

Foreclosures still plague California. In July, the state continued to lead the nation in foreclosures and Ventura County reported the eighth highest foreclosure rate in the U.S., according to foreclosure tracker RealtyTrac Inc of Irvine. That number, however, had dropped 7.8 percent since July 2011.

Another sign of recovery is that the nation's shadow inventory dropped in April to a four-month supply from a six-month supply, a 14.8 percent decline, and the lowest level in nearly three years, according to CoreLogic. Shadow inventory is made up of homes that are late 90 days or more on mortgage payments, in foreclosure and held as real estate-owned but not yet listed publicly for sale.